30. Reproductive tissue. Spermatogenesis. Spermatozoa.

The gonads consist of __________ which produce gametes.

ovaries and testes

The gametes in females and males are __________ and __________, respectively.

eggs; sperm

The formation of gametes is via __________.

meiosis

Satellite cells are present in male reproductive systems as __________ cells.

Sertoli

Satellite cells are derived from __________ germ cells.

primordial

Primordial germ cells develop in the __________ embryonal week.

3rd

Primordial germ cells are large cells with __________ cytoplasm and are PAS reaction positive.

light

The gonad is __________ at the indifferent stage.

indifferent

The formation of sperm occurs via meiosis and is called __________.

spermatogenesis

Spermatogenesis involves two processes: spermatocytogenesis and __________.

spermiogenesis

The first phase of spermatogenesis is called the __________ phase.

proliferative

In the growth phase, __________ and __________ spermatocytes form.

primary; secondary

The __________ phase involves spermatids transforming into spermatozoa.

transformation

DNA replication occurs before __________ begins.

meiosis

At the end of the first division of meiosis, we have __________ diploid cells.

2

The secondary spermatocyte gives rise to __________.

spermatids

The final part of spermatogenesis is called __________.

spermiogenesis

Nuclear condensation is a part of __________.

spermiogenesis

Flagellum formation is associated with the __________ of the sperm cells.

tail

The control of spermatogenesis is regulated by __________ hormones.

3

The hormones FSH and LH are secreted by the __________ glands.

pituitary

Testosterone is released by __________ cells.

Leydig

gonads

ovaries and testes which produce gametes

how are satellite cells split?

follicular cells in female and sertolli cells in male

satellite cells origin

primordial germ cells

primordial germ cells

• develop in the 3rd embryonal week in the wall of the yolk sac

• large cells iwth light cytoplasm and are PAS reaction positive

• cells proliferate and migrate to the primitive sex cords, giving rise to satellite cells

• the gonad is indifferent as one cannot morphologically distinguish it male or female

formation of sperm processes

divided into spermatocytogenesis and spermiogenesis

spermatogenesis

• starts at the beginning of puberty in the male testis and is a continuous process

• primitive germ cells called spermatogonia enlarge and become mitotically active

• cells undergo spermatogenesis, which diploid spermatogonia give rise to haploid spermatozoa

• during differentiation, spermatozoa move towards the lumen where they undergo mitosis, meiosis and maturation taking 64-74 days and coordiated by the sertoli cells, continues throughout life

formation of sperm 4 phases

1. proliferative phase - germ cells develop into spermatogonia

2. growing phase - primary and secondary spermatocytes form

3. maturation phase - spermatids form

4. transformation phase - spermatids transform into spermatozoa

spermatocytogenesis (first)

1. DNA replication before meiosis

2. spermatogonia give rise to primary spermatocyte

3. meiosis has 2 divisions the primary spermatocyte enters the first PMAT

4. at the end of the 1st division we have 2 diploid cells and primary spermatocyte give rise to secondary spermatocyte which enters the 2nd division of meiosis

5. at the end of meiosis each cell has a haploid set of chromosomes and each chromosome has only one chromatid

6. secondary spermatocyte give rise to spermatids

spermiogenesis (second)

1. the spermatids differentiate into sperm cells

2. nuclear condensation - reduction and condensation of the nuclear contents

3. acrosome formation - containing enzymes that penetrate through zona pellucida of the oocyte during fertilisation

4. flagellum formation - the tail of the sperm cells formed

5. cytoplasm reduction - elimination of all unnecessary cytoplasm

end of spermatogenesis left with sperm cell with a head, flagellum made of microtubules and mid-piece with mitochondria

what 3 hormones regulates the spermatogenesis?

Follicle-stimulating hormone (FSH), luteinizing hormone (LH) by pituitary gland and testosterone by leydig cells

semineferous tubules and leydig cells

where the sperm is made and they travel out of the tubules to the epididymis to mature and be ready for ejaculation, leydig cells make the testosterone

explain all spermatogenesis stages in detail

spermatocytogenesis

1. spermatogonium are between the sertoli cells and they undergo mitosis

2. one of the spermatogonium differentiate into the next precursor stem cell a primary spermatocyte and the other is left to continue mitosis

3. a tight junction separates the basal and laminal compartments between the sertoli cells, as soon as the primary spermatocyte gets close it will open and swiftly close to let it through the laminal compartment and prevent environments contaminating

4. primary spermatocyte’s cytoplasm will enlarge as it’s getting ready to divide

5. it undergoes meiosis I to produce 2 secondary spermatocytes, each primary spermatocyte has 23 pairs of chromosomes, each with a pair of sister chromatids, each secondary spermatocyte has 23 chromosomes

6. 2 secondary spermatocytes differentiate into 2 spermatids so 4 total

7. meiosis II begins so each spermatid only has 1 copy of each chromosome

spermiogenesis

8. spermatid differentiates into spermatozoa