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After the germinal epithelium... intratesticular genital ducts

Figure 10: Graphic illustrating the testis and its attached epididymis within the scrotum. The wall of the scrotal sac includes muscle and fascia that are not illustrated. There is a partial cavity formed by a serous lining, the tunica vaginalis. This cavity allows the testis to move within the scrotum, although full range of movement is not possible since it is anchored to the scrotum at its posterior surface.

C. Efferent Ductules

Figure 15: At higher magnification, details of the epithelium are apparent. The simple epithelium lining the efferent ductules has patches of short cells with microvilli and tall cells with cilia. Examples of these short and tall cells are labeled in the image.

Ovulation During each menstrual cycle, 12 to 20 primary follicles begin to develop into pre-antral follicles under the influence of FSH, but by day 9 only one of those secondary follicles remains, and it produces large amounts of estrodiol. When estrogen levels peak, there is a surge in the levels of LH and FSH from the anterior pituitary, which lasts for about 24 hours. Triggered by the surge in LH, the primary oocyte in the dominant follicle resumes meiosis I, producing a secondary oocyte that immediately progresses to the second meiotic division where it is arrested at metaphase until fertilization occurs. Prior to ovulation, the very large pre-ovulatory follicle spans the whole thickness of the ovarian cortex, causing a bulge on the surface of the ovary, called the follicular stigma.

A combination of hormonal changes and enzymatic effects results in the ovulation of the secondary oocyte. These changes include: as the dominant follicle grows, there is an increase in the pressure of the follicular fluid within the follicle caused by an increase in follicular fluid production and granulosa cell number. blood flow stops in a small area of the ovarian surface over the stigma, and the overlying germinal epithelium dies back exposing the white tunica albuginea the oocyte and corona radiata become loosened from the cumulus oophorus and membrana granulosa, proteolytic enzymes are secreted by the follicle, creating proteolysis of the follicular wall. a hole forms at the site of the follicular stigma the surface of the ovary ruptures contraction of smooth muscle fibers in the theca externa layer facilitate expulsion of the secondary oocyte The released secondary oocyte is now available to be fertilized by sperm. The ovarian follicle proper has reached the end of its lifespan.

Sequence of structures within the abdominal cavity

After entering the abdominal cavity, the ductus deferens passes anterior to the urinary bladder. The ampulla (4) of the ductus deferens is an expanded storage section for the spermatozoa at the distal end of the ductus deferens. It is joined by the seminal vesicle (labeled), a gland that arose embryologically as a diverticulum of the ductus deferens. This tube continues as the ejaculatory duct (5), which penetrates into the body of the prostate gland (labeled). Within the prostate gland, the right and left ejaculatory ducts flow into the prostatic urethra (6), the portion of the urethra that passes through the prostate gland). Beyond the point of the entrance of the ejaculatory duct, the male reproductive system becomes a midline structure, no longer consisting of bilaterally symmetric paired structures. From this point to the end, in the penile urethra (7), this tube serves the functions of both the urinary and the reproductive systems

Summary: Spermatogenesis Spermatogenesis is the process by which spermatogonia develop into spermatozoa. It involves several mitotic cell divisions of the spermatogonia, followed by meiotic divisions of spermatocytes. Refer to figure 8 below. The male germ cells arise from a population of stem cells and progenitor cells known as spermatogonia. The presence of a stem cell assures that men are able to continue to produce sperm into old age without fear of exhausting the supply of stem cells. The spermatogonia can be distinguished by slight morphological differences. The Type A spermatogonia are the stem and progenitor cells: a type A dark (Ad) spermatogonium is named for its dark heterochromatic nucleus. The Type Ad spermatogonia give rise to a two Type A pale (Ap) spermatogonia daughter cells that uniquely remain connected to each other by a cytoplasmic bridge, and this phenomenon of incomplete separation of daughter cells persists through all subsequent mitotic and meiotic cell divisions. As a result all progeny of the Type Ad spermatogonium are linked together, and this accounts for the patches of uniform progeny in the various regions of the seminiferous tubules. After several mitotic divisions, the type Ap spermatogonia differentiate into Type B spermatogonia, which represent the last cell capable of mitotic cell division. The type B spermatogonia give rise to primary spermatocytes, which double their DNA (as with mitotic cell division) but that DNA is subsequently divided twice in meiosis. In the first meiotic division, the primary spermatocytes separate paired homologous chromosomes and give rise to secondary spermatocytes, which are haploid in chromosome number but each chromosome consists of two chromatids, so DNA is the normal somatic cell amount. With meiosis II, the joined chromatids of the secondary spermatocytes separate into chromosomes, resulting in the haploid spermatids that now contain half the normal amount of DNA as well as half the number of chromosomes.

Because of the complicated process of meiosis I this stage of meiosis lasts up to 22 days. This prolonged stage is why the primary spermatocytes with their condensed chromosomes are commonly visible in the germinal epithelium. Meiosis II simply involves the separation of paired chromatids into daughter cells, which accounts for the speed at which that division occurs, and hence we see fewer secondary spermatocytes in the germinal epithelium. Two spermatids are formed as a result of the second meiotic division. The following phase, in which the spermatids undergo extensive cell remodeling, is spermiogenesis. The early spermatids undergo morphological changes that result in the formation of a gamete that requires little additional modification to successfully fertilize an oocyte. The spermatid develops a flagellum and the excess cytoplasm is separated from the modified nucleus. The Sertoli cell will phagocytose some of this residual body of cytoplasm. The process of spermiation involves the disengagement of the late spermatid from the apical membrane of the Sertoli cell. The released gamete is known as the spermatozoan (plural: spermatozoa).

the fundus, the corpus, and the cervix. endometrium for the mucosa/submucosa, ** changes in meriod myometrium for the thick surrounding muscularis layer** perimetrium for the serosa covering the outer surface.

Figure 25: This image of the endometrium sectioned in a plane oriented oblique to the lumen of the uterus illustrates the regular spacing of the uterine glands. The luminal lining invaginates into the lamina propria to form simple tubular glands. The endometrium in the lower left corner of the figure reveals simple tubular uterine glands that are sectioned slightly oblique to their long axis. To the right, the uterine glands are oriented perpendicular to the plane of section. The region of transverse sections reveals the very regular spacing of these glands. The stratum functionalis is the superficial layer and the one that undergoes cyclic changes in the hormone-driven uterine cycle. The stratum basalis is the thinner, deeper, permanent region; it is retained during menstruation and subsequently gives rise to the new stratum functionalis. The myometrium consists of interlacing bundles of smooth muscle obscurely arrayed in three layers. Branches of the uterine arteries within the middle muscle layer of the uterus form large arcuate arteries and a plexus of veins. The smooth muscle bundles in the inner and outer layers of the myometrium are predominantly oriented parallel to the long axis of the uterus. During pregnancy the uterus undergoes enormous enlargement, due to the hypertrophy of existing smooth muscle cells as well as to the development of new fibers through the division of existing fibers and the differentiation of resident mesenchymal cells.

As illustrated in the figure below, large arcuate arteries course in the middle muscle layer of the myometrium. The uterine arcuate arteries give rise to radial branches that, in turn, give rise to two sets of arteries that supply the endometrium: straight arteries, which are small branches that supply the the stratum basalis, and spiral arteries, the main branch of the radial artery, which continue upward into the stratum functionalis and becomes highly coiled. The straight arteries and the proximal portions of the spiral arteries do not undergo change during the menstrual cycle. However, the spiral arteries do respond to hormonal changes during the menstrual cycle, resulting in the degeneration of the stratum functionalis. No fertiliation = fall of corpous luteum = fall of progesterone = sprial arter constrcit + retat = ischemia = die

Figure 26: Image of the endometrium with its vascular supply drawn on the image. The myometrium is in the bottom of the field, below the stratum basalis of the endometrium. The uterine glands in the stratum functionalis are simple straight tubules during this stage. Radial arteries arise from the arcuate arteries; they reach the endometrium and branch into two types of arteries: the straight arteries which supply only the stratum basalis and the spiral arteries that supply the growing stratum functionalis.

Day 1: By convention, the average length of an individual menstrual cycle is 28-days and it begins with the first day of menstrual bleeding. Proliferative Stage: Stimulated by gradually increasing levels of estrogen generated by the growing preovulatory follicles in the ovary, menstrual fluid stops and the uterine lining begins to regenerate (day 5 to 14). Secretory Stage: Approximately mid-cycle the dominent follicle ovulates and the remains of the follicle becomes a corpus luteum, which produces large amounts of progesterone. Under the influence of progesterone the uterine lining prepares for potential implantation to establish pregnancy (day 15 to 28). Menstruation: If pregnancy does not occur in approximately two weeks following ovulation, the corpus luteum will involute and the woman's progesterone and estrogen levels drop. This drop in progesterone produces ischemia of the stratum functionalis and the cycle begins again with menstruation (day 1 to 5).

Figure 27: Relationship between the stages of the ovary (in blue), the days of the 28-day menstrual cycle (in black), and the stages of the uterus (in red). The dominant hormone of the follicular phase of the ovary is estrogen, and the dominent hormone of the luteal phase of the ovary is progesterone. With ovulation and termination of the Graafian follicle, the estrogen levels drop marking the end of the follicular phase, and in the absence of fertilization the corpus luteum involutes and progesterone levels drop, marking the end of the luteal phase.

Leydig cells and myoid cell Interstitial cells of Leydig occur in the angular interstitial spaces between the profiles of the seminiferous tubules, along with macrophages, fibroblasts, and myoid cells. In standard LM images, Leydig cells are large, ovoid, pale staining cells with frothy cytoplasm. Adult type Leydig cells differentiate in the postnatal testis and remain quiescent until puberty. When stimulated by the pituitary's luteinizing hormone (LH), Leydig cells produce testosterone. Peritubular myoid cells are present in the interstitium. Rhythmic contraction of these cells help propel the contents of the seminiferous tubules toward the rete testis.

Figure 9: Area of interstitial connective tissue between two seminiferous tubules. The basement membrane of the germinal epithelium is traced by a gray line on this image. Four of the the nearly 36 Leydig cells in this interstitial area are encircled. The frothy appearance of their cytoplasm is a characteristic feature of these endocrine cells.

Sequence of structures within the scrotum

Germ cells are produced in the seminiferous tubules of the testis (1). They are transported in a fluid produced by the Sertoli cells of the germinal epithelium that lines the seminiferous tubules. The fluid, conveying the sperm, is drawn into the rete testis of the testis, then via the efferent ductules to the ductus epididymis. Both the ductuli efferentes and the ductus epididymis are coiled tubules packed within the epididymis (2). The tail of the epididymis gives rise to the ductus deferens (3), which passes within the spermatic cord into the abdominal cavity.

Intro Path Male

Labeled diagram of the principal components of the male reproductive system. The path of the spermatozoa within structures from the seminiferous tubules in the testis to the penile urethra is sequentially numbered. The main accessory glands (prostate, seminal vesicle, and Cowper's) are labeled.

The epithelium of the tubules is engaged in progressive spermatogenic proliferation and differentiation. The following cells can be identified.

Sertoli cells (sustentacular cells) are solitary, irregularly-shaped tall cells, radially oriented, with their bases in contact with the the basement membrane of the tubule and their apical cytoplasm extending to the lumen. The nucleus lies a variable distance from the base of the cell; it is large, oval, irregularly indented, pale staining, and radially-elongated like the cytoplasm of the cell. A dark nucleolus is often prominent. The role of the Sertoli cell is structural, nutritional, phagocytic, and endocrine. The Sertoli cells secrete a fructose-rich fluid that nourishes the the sperm and enables the transport of the sperm to the duct system. Spermatogonia include the stem cells for sperm. These cells are also in contact with the tubules' basement membrane; their round-to-oval nuclei are near the basement membrane. The nuclei of spermatogonia vary in staining density depending upon the relative amount of euchromatin present, as a reflection of their synthetic activity. There are three different stages of the spermatogonia: the stem cell is the Type A-dense spermatogonia, the progenitor cell is the Type A-pale spermatogonia, and the precursor cell is the Type B spermatogonia. We don't morphologically distinguish between the three types of spermatogonia in this exercise, but they are illustrated below in figure 8. Spermatocytes are the largest germ cells. The nuclei of primary spermatocytes are prominent and typically exhibit chromatin organizing into chromosomes as these cells enter the final stages of meiosis I. Most of the spermatocytes observed in a tissue section are in the first meiotic prophase, which is a slow process, extending for about 22 days. The first meiotic division is followed by the more rapidly-progressing second meiotic division during which the daughter cells are termed secondary spermatocytes. For this reason (i.e., the brevity of meiosis II), there are relatively few secondary spermatocytes in tissue sections. We typically do not distinguish between primary spermatocytes and secondary spermatocytes in this material. Rather we tend to refer to the primary spermatocytes as just 'spermatocytes'. Spermatids are haploid cells. They will no longer divide, but will differentiate morphologically into mature spermatozoa. Spermiogenesis is the process whereby the spermatid undergoes this purely morphological transformation to acquire the final shape of the spermatozoa. There are two morphological types of spermatids: early and late. The nuclei of early spermatids are small, densely stained, and vary from round to slightly oval in shape. The late spermatids have distinctly radially elongated, dark staining nuclei, with their flagella extending into the lumen. Since the transformation of the early spermatids to late spermatids is a progressive event, you can expect to see some decidedly oval nuclei of intermediate spermatids. Late spermatids are similar in appearance to the mature spermatozoa except that their heads are embedded and bound in the indented apical plasma membrane of the Sertoli cells. Spermatozoa are cells with a small elongated head, no visible cytoplasm, and a long, slender tail that is mostly a flagellum. The residual cytoplasm of the maturing spermatid is left behind, often to be phagocytosed by the Sertoli cell or carried out with the sperm. The time required for a new type B spermatogonium to generate its full progeny of spermatozoa is 56 days.

Endocrine

The Endocrine System serves the body much the way the nervous system serves the body. However, whereas the nervous system responds to sensation, thought, and motor signals via electrochemical signals carried by neurons and axons, the endocrine system responds to metabolic activities of the body, as well as thought and motor activities, by releasing chemical signals (hormones) from endocrine cells that are carried to target cells by the blood circulatory system. In contrast to the nervous system's ability to send information very quickly, and which is relatively short-lived, the endocrine system's effects are typically slow to initiate and generally prolonged. Endocrine cells may be assembled together into multicellular glands, into distinct clusters or tissues, or may be incorporated singly into epithelia where they constitute components of the body's diffuse endocrine system. The response of endocrine cells to stimulus can be simple and direct, or involve several glands that signal each other in sequence. Control is typically through feedback mechanisms that modulate the secretions.

Overview Female The internal organs of the female reproductive system function together to produce and nourish offspring. They are situated within the woman's pelvis, and include the ovaries, uterine tubes, uterus, and vagina. The ovaries and oviducts are paired bilaterally-symmetric structures, while the uterus and vagina are single midline structures. Mammary glands, important for the nourishment of offspring, are not part of the female reproductive system but are covered in this exercise, mostly due to their role in lactation.

The female reproductive system basically consists of two main parts: the uterus and the ovaries; they are located within the body cavity. The uterus is associated with the ovaries via the oviducts, or Fallopian tubes. The internal reproductive structures are continuous with the external reproductive system structures at the vulva. The term adnexa is used anatomically to describe the parts adjoining an organ. In the case of the female reproductive system, the adnexa of the uterus are defined as the fallopian tubes and the ovaries, and sometimes the ligaments are included. Typically, the ovaries release the oocyte, which enters the oviduct. The motile spermatozoa can enter the oviducts after passage through the vagina, the cervix, and the uterus. If the sperm penetrates the oocyte, it fertilizes this female gamete. Subsequent union of the haploid gamete pronuclei creates the zygote, which after several days' passage through the oviduct, can implant into the prepared uterine lining and develop into a fetus.

The menstrual cycle Fertilization occurs in the oviducts. The zygote takes about 5 days to reach the uterus, by which time the uterine lining is ready to support it. At this time, the conceptus is a blasto with outer fetal placenta layer and an innermost mass of cells that will become the embryo. Broad Ligament: three subcompartments: the mesometrium, the mesosalpinx, and the mesovarium. Angle that occurs between the vagina, which is directed posteriorly in the pelvis and the anteriorly-tilted uterus, whose lumen typically approaches that of the vagina at a 90-degree angle.

The female reproductive system is designed to successful generate offspring over a period of nearly 40 years of a woman's life between puberty and menopause, and it normally does so on a regular cycle unless interrupted by a successful pregnancy. The women' ovary produces the female gamete, the ovum, and her body provides the site of its fertilization by the male gamete, the sperm. Fertilization occurs in the oviducts. The resulting zygote begins its journey along the oviducts toward the uterus where the conceptus will develop. At the time of ovulation, the uterus begins to prepare for the implantation and 9-month support of the developing child. Following fertilization of the freshly ovulated oocyte, the zygote takes about 5 days to reach the uterus, by which time the uterine lining is ready to support it. At this time, the conceptus is a sphere of cells called a blastocyst, which is composed of an outermost shell of cells that will give rise to the fetal placenta and an innermost mass of cells that will become the embryo. This cycle of repeated preparation for pregnancy is the menstrual cycle: hormones produced in the pituitary gland control the ovarian cycle, and the hormones produced in the ovary, control the stages of the uterine development. Figure 1: Illustration of the internal organs of the female reproductive system. On the left side of the drawing, the structures are illustrated in a midsagittal section. Not illustrated is the suspensory ligament of the ovary, which is hidden by the infundibulum of the oviduct in this image, and which carries the vessels and nerves to the ovary from the body wall. The suspensory ligament of the ovary should not be confused with the ovarian ligament, which is illustrated in the figure. The broad ligament is the fold of peritoneum that connects the uterus to the walls and floor of the pelvis. It is divided into three subcompartments: the mesometrium, the mesosalpinx, and the mesovarium. This frontal view of the organs does not show the angle that occurs between the vagina, which is directed posteriorly in the pelvis and the anteriorly-tilted uterus, whose lumen typically approaches that of the vagina at a 90-degree angle.

Figure 24: This tissue section of ampulla has somewhat less complex mucosal folds than the previous figure and the height of these folds appears to be less than that of the previous tissue section. In addition, the oviduct itself is of smaller diameter than the previous one. On this basis, this section is likely closer to the isthmus region of the oviduct than the previous one.

The isthmus is the narrow medial segment of the oviduct and it has a less folded mucosal lining. The muscularis is thicker than the height of any of the three mucosal folds, which at this point are more like ridges in the mucosa than folds. The intramural portion of the oviduct is about 1 cm in length. It has very shallow mucosal ridges. It is embedded within the wall of the uterus and therefore is surrounded by the uterine myometrium in place of a serosa. It opens into the uterine cavity.

Overview Male Repro

The male reproductive system is central to the human reproductive process. Its component parts function in the production, nourishment, temporary storage, and intermittent discharge of spermatozoa. The system consists of the two testes and the penis, and the intervening duct system that connects the testes, where the male gametes are produced, and the penis, which is the male genital organ. In addition, there are the accessory glands that contribute fluid secretions to the semen upon ejaculation. The male reproductive system is a bilaterally symmetric system, but becomes a single midline system when it connects to the urethra.

Seminiferous tubules Leydig + Myoid + Seminferous epithelium (stratified)

The seminiferous tubules are the structural and functional units of the testis. After puberty, the germ cells develop in the seminiferous tubules of the testis. The tubules are lined with a specialized stratified epithelium, known as germinal or seminiferous epithelium. CT: Leydig cells (testosterone) + myoid (contract propel to rete testis. Figure 3: Medium power view of a tissue section of the testis showing the tightly packed seminiferous tubules. There is relatively little interstitial tissue around the tubules, but what is there accommodates the blood and lymphatic vessels, as well as the testosterone-secreting Leydig cells and contractile myoid cells. The lumens of three regions of the tubule are labeled on the left side of this image. Look carefully and observe how the array of germ cells making up the epithelium varies from region to region.

A. Testis

Within the scrotal sac the testis is associated with the smaller epididymis, which is attached to its posterior surface. Both structures consist of packed tubules that differ both morphologically and functionally from the other. Seminiferous tubules, lined with the germinal epithelium, fill the testis. The epididymis contains two types of ducts, one of which is the ductus epididymis. A dense connective tissue capsule, the tough, membranous tunica albugínea of the testis, surrounds the testis. Another layer, the delicate tunica vascularis, is a highly vascular layer that underlies the tunica albugínea. The dense capsule of the testis is covered by a mesothelium which is part of the visceral layer of the serous membrane that is known as the tunica vaginalis. The testis and epididymis are attached to the posterior wall of the scrotum. Figure 2: Low power image of a testis from a one-day old child. The seminiferous tubules are not well developed at this stage, and so the packing that is so characteristic of the mature testis is not apparent, but the lobular organization is evident.Septa radiate from the mediastinum of the testis, which houses the rete testis, out to the encapsulating tunica albugínea. The septa divide the testis into about 250 lobules.

Ovarian Follicles Stages that begins with a primordial follicle and ends with the ovulation (expulsion) of a secondary oocyte from a Graafian follicle. Cocyte itself remains a primary oocyte until just before ovulation when it completes meiosis I and enters meiosis II.

primordial follicle: 1 layer follicular cell + BM + round dark nucleus + closest to tunic albuginea primary follicle: 1 layer granulos (previously foll) cells Zona Pellucida:GAG between granulosa and oocyte Theca folliculi: develops in stroma + exernal SM layer (theca externa) + sterid (theca interna pre-antral: many layers of granulosa antral follicle: antral fluid + mural granulosa + cumulus oophorus _ corona radiata preov: huge