Human Reproduction Test 1

Ovary is the primary sex organ of female reproductive system in human beings. Egg is released from one of the ovary each month. It also release hormone.

• Seminal plasma along with sperms forms the semen.
• The seminal plasma provides nourishment to sperms and rich in fructose and calcium ions.

The external genitalia are accessory structures of female reproductive system that are external to vagina they are also referred as vulva or pudendum the external genitalia includes the labia majora, mons pubis, labia minora, clitoris and glands within vestibules.

Testis is the primary sex organ in human male as it produce sperm or male gametes without which reproduction is not possible.

Male Reproductive System:

The innermost lining of the uterus is called the endometrium. It is the spongy layer that breakdown during the menstrual cycle along with mucus through the vagina.

Female Reproductive System:

• Each testis contains about 250 compartments called testicular lobules.
• Each testicular lobule contains one to three highly coiled seminiferous tubules that produce sperms.

• Sertoli cell is the “nurse” in testes that regulates germ cell proliferation and differentiation.
• One Sertoli cell supports a certain number of germ cells during these processes. 

• Seminiferous tubules of testis open into the vasa efferentia through rete testis.
• Rete testis is network of tubules inside the testis to store the sperm temporarily.

• Interstitial cells or Leydig cells are found adjacent to seminiferous tubules in the testicles.
• They produce testosterone in presence of luteinizing hormones.
• Leydig cells are polyhedral in shape and have a large prominent nucleus, an eosinophilic cytoplasm and numerous lipid-filled vesicles.

A mature ovarian follicle is called a Graafian follicle which consists of the antrum and follicular cells.

Structure of Graafian follicle:

 

• Mitochondria are called power-house of the cell.
• Sperms need energy for active movement.
• Middle piece of sperm contain large number of mitochondria.

Structure of Sperm:

• Half of the sperm contain X-sex chromosome and remaining half contain Y-sex chromosome.
• Hence two kinds of sperms are formed by human male.

• Each spermatid undergoes metamorphosis to develop into spermatozoa or sperms having head, neck and tail.
• Acrosome is present at the tip of head that contain enzyme for hydrolysis of wall of ovum during fertilisation.

• Three polar bodies.

  First one is produced when a mature primary oocyte transforms into a secondary oocyte. The first polar body divides again to produce two more polar bodies. When the secondary oocyte transforms into an ovum (mature), a polar body is generated. Hence, three polar bodies are produced during oogenesis.

  Oogenesis is the process of the formation of female gametes. It is a type of gametogenesis taking place in the female reproductive system. Here, the female gamete or ova are formed. This female gamete comes to be known as the ovum. Oogenesis involves three stages – pre-natal stage, antral stage, and Pre-Ovulatory Stage. 

  Once fertilization occurs, meiosis-II is said to be completed. This gives away the third polar body. In the event that fertilization does not take place, oocytes degenerate 24 hours post the ovulation while it is still arrested in the meiosis-II cell division. 

• In the secondary oocyte, the meiotic division is arrested at the metaphase stage.
• After ovulation, secondary oocyte passes into oviduct, where meiosis is completed only after the entry of sperm.

• At puberty, menstrual cycle begins in girls. The beginning of menstrual cycle is called menarche.
• It starts at the age of about 12 to 13 years in girls.

answer b)  It is made almost exclusively in the placenta. HCG hormone levels found in the mother's blood and urine rise a lot during the first trimester.

Transfer of male gametes (sperm) into female genital tract occurs during sexual intercourse that may leads to fertilisation of ovum for pregnancy. Sexual intercourse is called as coition or coitus.

The release of ovum from ovary during menstrual cycle is is called ovulation. Ovulation occurs in the middle of menstrual cycle that is on 14-16th day of start of menstrual cycle.

Endometrium is the inner lining of uterus which disintegrates and regenerates again and again during menstrual cycle.

• The movement of fetus is observed on fifth month of pregnancy.
• In first month heart is formed.
• In second months limbs and digits are formed.
• At the end of three months, all major organs and genital organs are formed.

The tail of the sperm, the flagellum, is what gives sperm motility.

• Mature mammalian sperm cell consists of a head, a neck, a middle piece and a tail.
• A plasma membrane envelops the whole body of sperm.
• The head of mature mammalian sperm is made of elongated nucleus covered by acrosome.
• The acrosome is filled with hydrolytic enzymes that help in fertilization of ovum.
• These enzymes called sperm lysins that dissolve the membranes enveloping the ovum and help the sperm cell to enter the ovum by penetrating egg membrane.

Lactiferous glands present inside the mammary gland start producing milk due to release of hormone oxytocin from pituitary glands.

• After parturition, mammary glands start producing milk. The yellowish coloured milk is called colostrums.
• This milk contains antibodies that provide immunity to newly born baby.