Male And Female Reproductive Structures

CONTENT

• Structures and Functions of the Reproductive System (Male and Female)
• Structure of the Gametes (Sperm and Ovum)
• Differences Between Male and Female Reproductive Organs

REPRODUCTIVE SYSTEM

Most multicellular animals and plants undergo a complex form of sexual reproduction in which especially differentiated male and female reproductive cells (gametes) unite to form a single cell, known as a zygote, which later undergoes successive divisions to form a new organism. The process takes place with the help of the system known as the reproductive system. This system can be divided into

• male reproductive system and
• female reproductive system.        

STRUCTURE AND FUNCTIONS OF MALE REPRODUCTION SYSTEM IN MAMMALS

STRUCTURE	DESCRIPTION	FUNCTIONS
Testis	Oval shaped, found in scrotal sacs in pairs outside the body to enjoy cooler temperature.	production of spermsproduction of male sex hormones (testosterone)development of secondary sexual character in male .
Seminiferous  tubules	Found within the testis, composed of a mass of sperm producing tubes.	Site of sperm production
Epididymis	Found outside the testis as a long coiled tube.	Collect and stores sperm temporary till maturity.
Vas deferens   (sperm duct)	A narrow tube which leads from epididymis to the seminal vesicles.	Conduction of sperm from epididymis to seminal vesicle.
Seminal vesicle	A small sac at the back of vas deferens.	Stores sperm till ejaculation.Secretes part of the seminal fluid. NOTE; Seminal fluid contains fructose  which provides energy for the sperms.
Prostrate gland	Connected to the urethra through many tubules	Secretion of seminal fluid.
Cowper’s gland	Located very close to the prostrate gland.	Secretes a part of the seminal fluid which raises the acidic ph of the female reproductive medium which otherwise can kill the sperm.
Urethra	A narrow tube which passes through the penis.	Aids the passage of sperm into the vagina of the female animal and also passage of urine out of the body hence it is called urinogenital opening.
Penis	Contains tissues which makes it turgid (erect when filled) with blood	Helps to introduce sperm into the vagina of the female animal and also passage of urine.

EVALUATION

1. Outline five structural parts of the male reproductive system and their functions

STRUCTURES AND FUNCTIONS OF THE FEMALE REPRODUCTIVE SYSTEM

	STRUCTURE	DESCRIPTION	FUNCTION(S)
1	Ovaries	Found on each side of the vertebra column (two in every woman)	– Produce eggs (ova) – produces female sex hormone (oestrogen and progesterone) – Development of secondary sexual characters in female.
2	Oviduct (fallopian tube)	A long narrow tube funnel opening which receives eggs released by the ovary and it is a linkage between ovary and uterus.	-Fertilization takes place in the oviduct – Allows the passage of egg from ovary to the uterus
3.	Uterus	A muscular organ which is a cavity for development of the zygote into a baby.	– Site of embryo development from implantation till birth
4.	Vagina	A muscular tube leading from the uterus to the outside of the body.	– It receives sperms from penis during intercourse -Allows the passage of foetus during birth
5	Cervix	A ring of muscles with tiny opening that closes the lower end of the uterus where it joins the vagina.	-Controls the opening and closing of  the vagina especially during birth.
6	Vulva	Refers to all external parts of the female reproductive organ	– Allows the passage of the penis into the vagina during intercourse. – permits passage of foetus during birth.
7	Clitoris	A small sensitive organ which correspond to the male penis. It is erectile and becomes stiff when stimulated due to blood inflow	Helps to stimulate female during sexual intercourse(experience  orgasm)

EVALUATION

1. State five structural differences between male reproductive system and female reproductive system.
2. Describe the organs in the female reproductive system.

STRUCTURE OF MAMMALIAN GAMETES

GAMETE

Gamete is a mature sexual reproductive cell having a single set of unpaired chromosome. It can be male or female gamete. They are formed in the gonads (testis on ovaries) through a process called gametogenesis.

MALE GAMETE

This is called sperm (or spermatozoa) and produced in the male gonads (testis) by a process called spermatogenesis. It is microscopic and unicellular in nature. Usually smaller and more elongated than the egg; about 0.05 mm (0.005 cm) long.

Spermatozoon consists of the following parts:

1. Acrosome: It can be found at the upper part of the head, containing lytic enzymes used to dissolve egg membrane to enhance penetration during fertilization.
2. Middle piece: It contains mitochondria for the generation of energy used by the sperm for swimming towards the egg.
3. Flagellum: The long whip-like tail for propelling the sperm cell
4. Nucleus: It can be found in the head of the sperm cell containing genetic materials (DNA-deoxyribonucleic acid) which fuses with the nucleus of the ovum at

fertilization.

FEMALE GAMETE

THE OVUM

This is called egg (ovum) and is produced in the female gonad (ovary) by a process called oogenesis. This is larger than sperm, about 0.1mm in diameter.

Each ovum is made up of the following

• Cytoplasm
• A central Nucleus: It contains the chromosomes which carry the genes.
• Granules and yolk droplets: A source of nourishment for the embryo at the early stage of development.
• Plasma membrane:  It surrounds the cytoplasm.
• Outer vitelline membrane and jelly coat of glycoprotein.

Note: The nuclei of the sperm and ovum contains chromosome which carries the gene that are responsible for transmission of characters from parents to offspring.

GENERAL EVALUATION

1. What is reproduction?
2. Draw a well labeled diagram of the male reproductive organ in mammals.
3. List five structural parts of the female reproductive organ in mammals and state their functions.
4. State five distinct differences between the male and female reproductive organs in mammals
5. Differentiate between the male and the female gametes in mammals.

READNG ASSIGNMENT

College Biology, chapter 16, pages 292-324

WEEKEND ASSIGNMENT

SECTION A

1. The following are female sex hormone except A. oestrogen B. progesterone C. testosterone D. oxytocin
2. The site of production of sperm is A. epididymis B. seminiferous tubules C. seminal vesicle D. penis
3. Fertilization takes piece in the A. uterus B. vagina C. oviduct D. vulva
4. ____ parts of the male gamete dissolve the egg membrane to enhance penetration A. nucleus B. acrosome C. flagellum D. vitelline membrane
5. The process by which the male and the female gamete are formed in the gonads is referred to as  ____ and ­­­­­­­­­_____

SECTION B

1. Draw a well labeled diagram of the sperm cell and state the functions of the labeled parts.
2. Differentiate between sexual and asexual reproduction