Testis, and Spermatogenesis

Question 1

The straight seminiferous tubules open into …………..

Answer 1

Rere testis

Question 2

Leydig cells are contained in ……………..

Answer 2

The connective tissue in which seminiferous tubules are embedded contains the interstitial cells of Leydig

Question 3

…………………. cells are the source of testosterone

Answer 3

Leydig cells

Question 4

Mention the two elements of the basement membrane of the seminiferous tubules

Answer 4

spermatogenic cells
supportive cells/sustentacular cells of Sertoli

Question 5

………………… provide mechanical support, protection and probably nutrition for the developing germ cells

Answer 5

Sustentacular cells of Sertoli

Question 6

Define spermatogenesis

Answer 6

The entire sequence of events leading to transformation of germ cells into spermatozoa (sperms)

Question 7

Spermatogenesis is divided into ………..

Answer 7

spermatocytogenesis and spermiogenesis

Question 8

What is spermacytogenesis?

Answer 8

The process by which germ cells or spermatogonia become spermatocytes

Question 9

Outline the sequence of events in spermacytogenesis

Answer 9

• The sex cords acquire lumen and become the seminiferous tubules
• The primordial germ cells give rise to spermatogonia.

The spermatogonia formed are of two types; Type A and Type B spermatogonia

• Type A spermatogonia divide by mitosis to provide a continuous reserve of stem cells
• Some Type A cells give rise to successive and progressively more differentiated generations of type A spermatogonia. The generations range from 4 to 7
• Type B spermatogonia form on completion of the last generation/division of the type A cells
• Secondary spermatocytes are formed by primary spermatocytes after 22 days in prophase and rapid completion of meiotic 1 division
• Spermatids form after second meiotic division of the secondary spermatocytes
• spermiogenesis occurs and and spermatids are transformed into spermatozoa

Question 10

Both secondary spermatocytes and spermatids are haploid cells, true or false

Answer 10

True

Question 11

The daughter cells of spermatogonia up to spermatids are connected by ……………… due to incomplete division of the cytoplasm

Answer 11

Intercellular bridges

Question 12

………… cells assist in the release of mature spermatozoa

Answer 12

Sertoli

Question 13

What is spermiogenesis?

Answer 13

The differentiation process that leads to the transformation of spermatids into spermatozoa

Question 14

Spermatogonia, up to spermatozoa are embedded in deep recess of Sertoli cells, true or false

Answer 14

False
Only spermatogonia, up to spermatids are embedded in deep recess of Sertoli cells

Question 15

Outline the changes that occur in spermiogenesis

Answer 15

• Formation of acrosome
• Condensation of nucleus into a dense mass (head)
• Formation of neck, middle piece and end piece
• Shedding of most of the cytoplasm

Question 16

In humans, how long does it take for a spermatogonium to develop into a mature spermatozoon or mature sperm

Answer 16

it takes about 74 days

Question 17

Sertoli cells are also called ………..

Answer 17

sustentacular cell

Question 18

Shortly before puberty, the sex cords acquire a lumen and become the ………………..

Answer 18

Seminiferous tubules.

Question 19

………….. covers half of the nuclear surface and contains enzymes that assist in penetration of the egg and its surrounding layers during fertilization

Answer 19

Acrosome

Question 20

Most of the cytoplasm as residual bodies that are phagocytized by …………….

Answer 20

Sertoli cells

Question 21

………………… forms the acrosomal cap

Answer 21

Golgi apparatus

Question 22

……………… moves towards one pole of the cell to form the head of the spermatozoon.

Answer 22

the nucleus

Question 23

How is the axial filament formed?

Answer 23

One of the centrioles (formed from the division of the centrosome) becomes spherical and moves towards the posterior end of nucleus to occupy the neck region. It gives rise to the axial filament.

Question 24

How is the annulus formed?

Answer 24

The other centriole (formed from the division of the centrosome) moves away from the first centriole and becomes ring shaped. It forms an annulus/ring around the distal end of the middle piece through which axial filament passes.

Question 25

Describe the middle piece

Answer 25

The part of the axial filament between the neck and annulus becomes surrounded by the mitochondria, and together with them forms the middle piece.

Question 26

How many spermatozoa is formed from one primary spermatocyte?

Answer 26

One primary spermatocyte gives rise to 4 spermatozoa

Question 27

What is the use of the polar body in oogenesis?

Answer 27

The polar body is used to get rid of the unwanted chromosomes

Question 28

Describe the processes of formation of the ovarian follicle

Answer 28

- Some cells of the stroma become flattened and surround the oocyte - The flattened cells form the ovarian follicle and are called follicular cells - The primary oocytes, surrounded by the layers of the flat epithelial (follicular) cells and are primordial follicles - A layer of glycoproteins appears between oocyte and follicular cells, it is called the zona pellucida - The follicular cell proliferate and form several layers called granulosa cells (membrana granulosa) - A cavity (antrum) appears within the granulosa forming a follicle - The cavity of the follicle increases in size and the wall of the follicle becomes thin - The oocyte now lies eccentrically surrounded by granulosa cells called cumulus oophorus - Cells that attach it to the wall of the follicle is called discus proligerus - As the follicles expands, the stromal cells surrounding the granulosa organize into an inner layer of secretory cells (theca interna) that secretes oestrogen and an outer fibrous capsule (theca externa).

Question 29

What is referred to as the zona pellucida?

Answer 29

A layer of glycoproteins appears between the oocyte and follicular cells

Question 30

The follicular cell proliferate and form several layers called …………………

Answer 30

Membrana granulosa/granulosa cells

Question 31

What is an antrum?

Answer 31

A cavity that appears within the granulosa

Question 32

Outline the characteristics of the human semen

Answer 32

- It consists of sperms produced by seminiferous tubules of testes and secretion of seminal vesicles, prostate, and bulboure- thral glands. - The average volume of ejaculate is 2.5–3.5 ml. - Semen has a pH of 7.35–7.5 - Average sperm count of semen is 100 million per ml. - It is white and opalescent. - The approximate contribution by various reproductive glands is as under: • Seminalvesicles:60% • Prostate:30% • Testes:5% • Bulbourethral glands: 5% - The milky secretion of the prostate gland is alkaline in nature and neutralizes the acidic pH of the vagina. - The enzymes of prostatic secretion break down the coagulated proteins secreted by seminal vesicles and make the semen more liquid

Question 33

The movement of sperms is best at pH of ……..

Answer 33

6–6.5

Question 34

The absence e of motile or viable sperm is referred to as ……

Answer 34

Azoospermia