Sertoli & Leydig cells

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NADPH

CYP11A1/P450 catalyses oxidation of cholesterol by using electrons from what?

Gonadotropin releasing hormone GnRH

Hormone from hypothalamus that promotes secretion of follicle-stimulating hormone (FSH) and luteinizing hormone (LH)

Mullerian inhibiting substance MIS

a hormone released by sertoli cells that causes regression of the mullerian ducts (which go on to form female reproductive system) - important in sex determination

50-100ug/day

approx dihydrotestosterone (DHT) production rate

10-15ug/day

approx estradiol production rate

5mg/day

approximate testosterone production rate

tight junctions

by what are sertoli cells held together?

5a reductase = DHT, aromatase = estradiol

catalytic enzymes and products of testosterone conversion

aromatase cyp19

converts small amount of leydig cell derived testosterone to potent estradiol 17b (estrogen)

androgen response element

dimerisation and phosphorylation of DHT/Testosterone bound Androgen Receptor cuases formation of what?

glycolysis

due to the blood testis barrier, sertoli cells are responsible for providing substrates for what?

p450

enzyme system responsible of translocation of cholesterol and production of testosterone

5a reductase

enzyme that converts testosterone to DHT

proteases and protease inhibitors

glycoproteins secreted by sertoli cells involved in tissue remodelling during spermination and movement during spermatogenesis

at least 1

how many isoforms of the estrogen receptor (ER) are expressed on sperm cells?

cholesterol hydrolysis and expression of StAR

immediate effects of LH stimulating cAMP-PKA pathway in leydig cell

sertoli cell glut1 transporter -> metabolised to lactate -> sperm specific lactate transporter

journey of glucose in sertoli cell to germ cell

increased steroidogenic enzymes and LDL receptors

longer term effects of LH stimulating cAMP-PKA pathway in Leydig cell

secretion of ferric ions and synthesis of testicular transferrins

movement of iron through sertoli cells results in what?

growth and paracrine factors

number 1 function of sertoli cells is to provide what

LH stimulates cAMP-PKA pathway -> cholesterol translocation via StAR -> pregnenolone -> translocation to ER -> testosterone

pathway of testosterone production in leydig cell

inhibin

protein hormone secreted by sertoli cells, inhibits FSH secretion, helps regulate sperm production

constant / direct

relationship between sertoli cell number and germ cell number

DHT

required for masculinization of external genitalia, development of prostate gland and changes associated with puberty

their antigens stimulating autoimmunity

the blood-testis barrier isolates spermatocytes and spermatids from the immune system to prevent what?

transferrin, ceruloplasmin

transport/bioprotective proteins secreted by sertoli cells in high abundance

LH = interstitial/leydig cells, FSH = sertoli cells

upon what do each of the 2 hormones secreted by pituitary glands act?

negative feedback of LH release

upon what does circulating testosterone have an effect/regulate

glycoproteins

what are secreted by sertoli cells to help maintain biochemistry within system

transport, proteases & inhibitors, basement membrane, regulatory

what are the types of (functions of) glycoproteins that are secreted by the sertoli cells?

CYP11A1 / p450scc

what catalyses the conversion of cholesterol to pregnenolone via 3 oxidation reactions in the same site

diffusion of materials between cells

what do the tight junctions that hold sertoli cells together limit?

DHT binds with greater affinity

what is the difference between testosterone and DHT binding with Androgen Receptor?

can translocate into nucleus

what is the importance of the formation of the Androgen Response Element complex (ARE)?

lactate

what is the preferred substrate for glycolysis in primary spermatocytes?

allow movement of iron through

what is the role of transferrin receptors on sertoli cells

blood testis barrier

what isolates luminal fluid from the fluid bathing the cells in the basal compartment to protect sperm cells from immune attack (antibodies)

sertoli cells

what produces aromatase (CYP19)?

androgen binding protein

what protein do sertoli cells make and secrete

luminal

what sort of fluid is secreted by sertoli cells

regulatory

what type of glycoproteins secreted by sertoli cells are lowest in abundance

type 2

which of the 2 isoforms of 5a reductase is the most important

appear after puberty

why would spermatocytes and spermatids be recognised by the immune system as 'foreign' cells


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