spermatogenesis

Question 1

Testicular anatomy

Answer 1

Seminiferous tubules drain into the rete testis > drain into 5-10 efferent ducts > head of epididymis > body > tail > vas deferens

Question 2

Avg human testis

Answer 2

20cc

Question 3

Define spermatogenesis

Answer 3

The process by which a spermatogonial stem cell gives rise to a spermatozoon

Question 4

Describe the three phases of spermatogenesis

Answer 4

1. Proliferative phase: spermatogonia proliferate to give rise to spermatocytes while also self-renewing. 2. Meiotic phase: spermatocytes undergo meiosis. 3. Spermiogenic phase: spermatids mature into spermatozoa

Question 5

Types of spermatogonial cells

Answer 5

Type A (dark), Type A (pale) and type B. Type Ad differentiate into type Ap. Type Ap differentiate into Type B which further divide to produce preleptotene spermatocytes that enter meiosis

Question 6

Meiosis phase

Answer 6

primary spermatocyte > 2 secondary spermatocytes (first meiosis) > 4 spermatids (second meiosis)

Question 7

number of chromosomes during stages of spermatogenesis

Answer 7

Type A/B spermatogonia have 46 chromosomes. Primary spermatocyte undergoes DNA replication (still 46 chromosomes). Secondary spermatocyte has 23 chromosomes (homologous chromosomes are separated). Spermatids also have 23 chromosomes (meisosis II separates sister chromatids)

Question 8

List the stages of spermiogenesis

Answer 8

Golgi phase, Cap phase, Acrosomal phase, and Maturational phase

Question 9

Describe the golgi phase of spermiogenesis

Answer 9

large acrosomal vesicles are elaborated by the Golgi appartus and soon become the most prominent cytoplasmic inclusion within the spermatids.The acrosomal vesicles move gradually to one end of the nucleus, and the centrioles move to the other end.

Question 10

Describe the cap phase of spermiogenesis

Answer 10

Acrosomal vesicles become the acrosomal cap of the sperm. The centriole extends away from the nucleus to form the tail, pulling most of the cytoplasmic inclusion away from the nucleus.

Question 11

describe the acrosomal phase of spermiogenesis

Answer 11

Mitochondria are sequestered at base of tail.

Question 12

describe maturational phase of spermiogenesis

Answer 12

Excess cytoplasm is cast off from cell completing the maturation process

Question 13

Spermiation

Answer 13

Mature spermatozoa are released and deposited to the lumen by sertoli cells.

Question 14

Functions of epididymis

Answer 14

Storage of spermatozoa, posttesticular maturation (spermatozoa develop motility, become capable of fertilizing and undergo capacitation)

Question 15

Compare the functions of the three regions of the epididymis

Answer 15

head (caput): concentrates spermatozoa. Body: maturation. Tail (cauda): storage

Question 16

Time course for spermatogenesis

Answer 16

64 days from spermatogonia to spermatozoa. Sperm are constantly developing

Question 17

sertoli cells functions

Answer 17

forms the blood-testis barrier, support and nutrition, movement/release of germ cells, secretes tubule fluid, androgen binding protein and inhibin

Question 18

Where in the epididymis are sperm capable of fertilizing

Answer 18

Generally, spermatozoa taken from the caput or proximal corpus are generally incapable of fertilization, whereas those from the distal corpus and the cauda are able to undergo capacitation and achieve normal gamete interaction.