Biology M.C.Q (1 Marks)

Sustentacular cells are the cells that are associated with providing structural support.
A type of sustentacular cells is Sertoli cells which are found in the stratified epithelium of seminiferous tubules.
Sertoli cells are also known as supporting cells.
They are elongated and pyramidal which partially envelope the spermatogenic cell which nourish the spermatozoa.

In the embryonic developmental stage, an embryo develops within the amniotic sac, under the lining of the uterus.
This stage is characterized by the formation of most internal organs and external body structures.
It is also characterized by the stage of development resembling other species.

The inside of the testes is divided into small compartments called lobules.
Each lobule contains a section of seminiferous tubule lined with epithelial cells.

Acrosome reaction in sperm is triggered by release of fertilizin. The secretions of the acrosome help the sperm enter into the cytoplasm of the ovum through the zona pellucida and the plasma membrane.

Oestrogens regulate growth and development of female accessory reproductive organs, secondary sexual character and sexual behavior.

The endocrine gland refers to that gland in an organism that secretes the hormones directly into the circulatory system that needs to be carried to a distant site.
Leydig cells, are the cells that secrete the male sex hormone, testosterone directly to the circulatory system.
They are located in between the seminiferous tubules within the testes.

Vas deferens is the tube that connects the testes with the urethra.
The vas deferens is a coiled duct that conveys sperm from the epididymis to the ejaculatory duct and the urethra.
Vas deferens is the duct that conducts sperms from testis to body cavity.
Ureters are the ducts that transfer urine from kidneys to urinary bladder.
Urethra is the common duct for transfer of urine and sperms in males, it arises from urinary bladder and opens to outside.

During fertilisation, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms. Thus, it ensures that only one sperm can fertilise an ovum.

The vas deferens receives duct from the seminal vesicle and opens into urethra as ejaculatory duct.

The embryo shows multiplicative growth as this kind of growth refers to the increase in the number of cells of the organisms due to mitotic cell division. And as the embryo is developing, it will have many mitotic divisions.
Hence, this multiplicative growth is also called as embryonic growth.

(C) Progesterone.

The ductus deferens is also known as the vas deferens.
It is present in a male reproductive system that carries sperm from the epididymis to the ejaculatory duct.

The uterine lining dies due to the deficiency or reduced level of progesterone in blood and is sloughed off.
Blood vessels rupture, causing bleeding.

Teratology is the study of abnormal embryonic growth, abnormal formations and congential abnormalities.
Ontogeny is the study of developmental history of an organism which starts from fertilization to the maturation of organism.
Morphogenesis is the origin and development of morphological characteristics.
The study of morphological character is known as morphogenesis.
Parthenogenesis is a mode of asexual reproduction in which growth and development of embryos occur without fertilization.
In animals, parthenogenesis means development of an embryo from an unfertilized egg cell.

Cowper's gland is also known as bulbourethral gland.
It is an exocrine gland present in male reproductive system.
It provides lubrication to the distal urethra and neutralize the acidic urine which is present in the urethra.

Sertoli cell is the "nurse" cell of the testes and is located in the seminiferous tubule.
They are somatic cells located within the germinal epithelium.
Its main function is to nourish the developing sperms, hence called as "nurse" cells.

Holoblastic cleavage is that in which the cleavage furrow divides the egg completely and the blastomeres formed may be equal or unequal in size.
It occurs in alecithal or microlecithal eggs.
Generally, the mammalian egg is alecithal, meaning no yolk.

Depending on the amount of yolk present in the egg, cleavage can be holoblastic or meroblastic.
Holoblastic is the total or entire cleavage, while meroblastic is the incomplete or partial cleavage.
In the absence of large concentration of yolk, holoblastic cleavage is seen.
In the presence of a large amount of yolk in the fertilized egg cell, the cell undergoes partial or meroblastic cleavage.

The nucleus is present in the head. Acrosome releases enzyme which dissolves zona pellucida. Tail helps in swimming of sperm and middle piece is the place where mitochondria are present.

The seminiferous tubule is lined on its side by two types of cells called male germ cells which undergo meiotic divisions finally leading to sperm formation and sertoli cells provide nutrition to germ cells.

Seminiferous tubules are located within the testes and are the specific location for meiosis and the spermatozoa formation.
The wall of the seminiferous tubules is called germinal epithelium.

Bartholin's glands are located on either side of the vaginal opening and secrete a fluid that assists in vaginal lubrication.
Hence, Bartholin’s glands are located on either side of the vagina in humans.