spermatogenesis

Question 1

spermatogonia?

Answer 1

spermatogonia are diploid germ cells in the testes that maintain their numbers by mitosis, tus maintaining spermatozoa numbers through life.

they contain both X and Y sex chromosomes. at a certain point, a spermatogonium will stop its other duties and begin meiosis

Question 1

in males meiosis occurs during spermatogenesis, in which spermatogonia in the testes become ?

Answer 1

spermatozoa

Question 2

when does spermatogenesis occur

Answer 2

at puberty

Question 3

what are two parts to spermatogenesis?

Answer 3

• spermatocytogenesis
• spermiogenesis

Question 4

what is spermatogenesis

Answer 4

when germ cells in the seminiferous tubules become haploid spermatozoa (mature sperm)

Question 5

what is spermatocytogenesis?

Answer 5

first stage of spermatogenesis
- spermatogonia A cells -> spermatogonia B cells - meosis I
- divide until become primary spermatocytes (diploid) (homologous recombination occurs)
- meosis II secondary spermatocytes (haploid) - spermatids (haploid)

Question 6

spermiogenesis?

Answer 6

• rounded spermaid cell changes shape, becoming elongated and developing the familiar head and tail

Question 7

what does the acrosome of sperm contain and what is its function

Answer 7

contains enzymes
help sperm penetrate outer layers of ovum during fertilization

Question 8

where does mitochondria go in sperm

Answer 8

concentrated in first part of tail

Question 9

when spermatids become spermatozoa do they lose their cytoplasm?

Answer 9

yes and the nucleus is packed into the head

Question 10

what hormones are in charge of regulation of spermatogenesis?

Answer 10

GnRH from hypothalamus
LH and FSH from anterior pituitary

Question 11

what does LH stimulate leydig intersitial cells to do?

Answer 11

production of testosterone
LH indirectly promotes spermatogenesis by inc intratesticular testosterone (promotes maturation of sperm)

Question 12

what does FSH do?

Answer 12

stimulates sertoli cells to support spermatogenesis (sertoli cells are required for the progression of spermatogonia to sperm)

Question 13

what do sertoli cells look like and where are they found?

Answer 13

found as irregular columns in shape in a simple columnar epithelium and they extend from the basement membrane to the luminal surface of the seminiferous epithelium.

recognised by their prominent nucleoli

Question 14

what do Sertoli cells do?

Answer 14

support and nutrition of developing germ cells
compartmenalization of seminiferious tubule by tight junctions which provides a protected environment for germ cells
controlled release of mature spermatids into tubular lumen
secretion of fluid, proteins and growth factors
phagocytosis of degenerating sperm cells.

Question 15

what two hormones downregulate LH and FSH secretion by negative feedback loops?

Answer 15

testosterone and inhibin B

Question 16

what produces Inhibin B?

Answer 16

sertoli cells
under stimulatory influence of FSH and acts to inhibit FSH secretion from the pituitary.