Chapter 36 Development

The anatomical location for the typical union of a sperm and an egg (conception) is the _____.

oviducts

Choose the correct developmental sequence of animal development.

fertilization → cleavage → gastrulation → organogenesis

Which five of the following statements are true about organogenesis in a frog embryo?

...

After fertilization, embryonic development progresses through three stages:

1. During cleavage, the cytoplasm of the zygote is divided into many different cells called blastomeres. By the end of cleavage, the embryo is called a blastula, which is a ball of cells surrounding a fluid-filled cavity called a blastocoel. 2. During gastrulation, the embryo is called a gastrula. In this stage, cells undergo dramatic rearrangement, forming the embryonic germ layers and other structures, such as the blastopore. Once gastrulation is complete, the major body axes of the embryo (anterior-posterior and dorsal-ventral) are visible. 3. During organogenesis, the three embryonic germ layers develop into the rudiments of organs. Structures such as the notochord, the neural tube, and somites form. Somite cells undergo differentiation, giving rise to different body tissues and organs, including the skeleton, muscles, and skin.

The allantois stores nitrogenous wastes in a reptile egg. What is the function of the allantois in human development?

The allantois helps form the umbilical cord in human development.

Among the following, the earliest consequence of the acrosomal reaction is _____.

the membrane of the egg depolarizing

In an embryonic vertebrate, the zone of polarizing activity (ZPA) is a block of tissue located on the posterior side of a limb bud. The ZPA provides information about the anterior-posterior axis of the limb. Cells nearest the ZPA form the most posterior of digits (like our little finger); cells farthest from the ZPA form the most anterior digits (like our thumb). How would a vertebrate forelimb bud develop if it had two zones of polarizing activities, one on the posterior side and one on the anterior side of the bud?

The forelimb bud would develop with extra digits, in a mirror image arrangement to the normal digits.

An embryonic cell that is "totipotent" is one that can _____.

by itself, give rise to the entire embryo, as cleavage proceeds

The first stage of embryonic development is _____. This process produces _____.

cleavage ... a cluster of cells

During human gestation, rudiments of all organs develop

in the first trimester

The mesoderm gives rise to _____.

skeletal and muscular systems

Oxytocin secretion and milk release from the mammary glands of lactating female mammals are initiated by _____.

the physical sensation of the baby sucking at the nipple