[3] Amphibian spermatogenesis

thick outer covering of the testis composed of thick connective tissue.

tunica albuginea

tiny convoluted tubules w/c appear as round or oval structures with varied sizes containing the spermatogenic cells.

seminiferous tubules

the outer envelope of a seminiferous tubule. Note the form of cells adhering to it.

basement membrane

round compartments that enclose the cells in the same stage of spermatogenesis.

spermatocysts

There is a ___ arrangement of spermatocysts in the tubule such that cells in the early stage maybe located adjacent to cells in the latter stage of development. Different cell types are best discerned using ___.

random; oil immersion objective (100x)

male germ cells undergoing maturation division locate inside the spermatocysts

spermatogenic cells

in their natural order of development, the spermatogenic cells are as follows:

1. residual spermatogonia

2. active spermatogonia

3. primary spermatocytes

4. secondary spermatocytes

5. spermatids

6. spermatozoa

small cells with irregular dense nuclear materials. Their small spermatocyst is interspersed among the bigger spermatocysts. They are inactive in cell division and serve as the reserve cells for the next breeding period.

residual spermatogonia

large cells close to the periphery of seminiferous tubules. They are actively dividing cells with prominent nuclei and threadlike chromatin materials

active spermatogonia

large cells with varied morphology depending upon the stage of prophase I. The chromosomes appear as thread-like and scattered but others are thick, basophilic and tightly packed

primary spermatocytes

small cells that are half the size of the primary spermatocytes. They have condensed nuclei and a thin ring of cytoplasm around it.

secondary spermatocytes

tiny, rounded or elongated cells with densely stained nuclei. They undergo spermeiogenesis which account for their varied forms and sizes.

spermatids

cluster of minute cells appearing as clumps of black rods or “walis tingting”. The heads of the sperms are seen only with OIO.

spermatozoa

non-spermatogenic cells that provide support to the germ cells

somatic cells

what are the somatic cells in the testes

• sertoli cells

• interstitial cells

columnar or pyramidal cells that adhere to the basement membrane or lying among the germ cells. They have oval nuclei and prominent nucleoli. The cell outline is not well defined under light microscope.

sertoli cells

large, pale and ovoid cells that occur in cluster between the seminiferous tubules. They are responsible for the synthesis of testosterone, the male sex hormone

interstitial cells

interstitial cells are also known as ____

leydig cells

the number of sperm cells is ____ throughout the life of the organism. meiosis is ____: not arrested

kept; continuous

spermatogenesis occurs in the ___ specifically in the ____

testes; seminiferous tubules

where sperm cells are taught to be motile and wait to be released

epididymis

secrete testosterone (needed as it is a precursor)

leydig cells

keeps sertoli cells together; for integrity

tight junctions

for support and provides nourishment

sertoli cells

the ____ releases ____ which stimulates the ____ to secrete ___

hypothalamus; gonadotropin-releasing hormone (GnRH); anterior pituitary gland; gonadotropins

what are the gonadotropins secreted by the anterior pituitary gland

• follicle-stimulating hormone (FSH)

• luteinizing hormone (LH)

FSH acts on ___ to produce ___, which binds testosterone, maintaining high local concentration in the seminiferous tubules

sertoli cells; androgen-binding protein (ABP)

LH stimulates the ____ to produce ____, which is synthesized from cholesterol and is lipophilic

leydig cells; testosterone

spermatogenesis occurs in the ____ of the seminiferous tubules, where maturing sperm are supported by sertoli cells and exposed to the high testosterone levels facilitated by ABP

adluminal space

what are the parts of the sperm

• head

• midpiece

• tail

the head of the sperm contains the:

plasma membrane, nucleus, centriole

head: at the tip they are ___-rich for breaking down the ___ (hydrolytic enzymes) = ___

golgi; zona pellucida; acrosome

midpice: ___-rich providing energy for swimming

mitochondria

tail: cannot move without ___. contains the ___ which propels the head forward in an undulating motion

ATP; flagellum

Process of development and maturation of male gametes (or spermatozoa) that starts in the embryonic testis and is completed in the sexually mature testis

spermatogenesis

• Youngest cells in the series

• Round cells with round or oval nucleus that occupy the 1st layer or basal layer of spermatogenic cells

• Lie against the basal lamina of the seminiferous tubule

spermatogonia

• Largest cells in the series

• They are round cells that occupy the 2nd to 4th layer of the spermatogenic epithelium

• They have a dense round nucleus due to condensation of chromatin material into chromosomes

primary spermatocytes

These cells are not commonly found in sections of seminiferous tubule because as soon as they are formed from primary spermatocytes, they immediately divide into daughter spermatids

secondary spermatocytes

Secondary spermatocytes enter ___ immediately after being formed from primary spermatocytes during ___

meiosis II; meiosis I

small round cells with round nucleus and nucleolus located above the layers of primary spermatocytes

early spermatids

small cells with oval dense compact nucleus and a short tail and embedded in the cytoplasm of Sertoli or sustentacular cells

late spermatids

tall columnar cells that occur individually at regular intervals in the seminiferous tubule

sertoli cells

• Cells with head, neck and tail (middle piece and principal piece), which form a mass in the lumen of the sexually mature seminiferous tubule

• Middle piece of the tail connects with the neck and appears darker than the principal piece of the tail

• The shape of the head varies in some species

spermatozoa

changes that occur in the spermatid: nucleus

head becomes compact

changes that occur in the spermatid: centriole

• becomes located in the neck of the sperm

• gives off a filament: axial filament of the tail

changes that occur in the spermatid: cytoplasm

is reduced: envelope around the head, middle piece, and tail

changes that occur in the spermatid: golgi apparatus

acrosome

changes that occur in the spermatid: mitochondria

arranged in helical manner: spiral filament of middle piece

transverse section through an adult frog testis

section through part of a frog testis

transverse section through seminiferous tubules of a frog testis

transverse section through part of a frog seminiferous tubule

transverse section through part of a frog seminiferous tubule