Lecture 1: Reproductive organs
The male and female reproductive organs are used for producing, storing, nourishing
and transporting gametes.
The process of fertilization is defined as the fusion of male and female gametes to form
a zygote
Definitions:
o The gonads produce gametes + hormones to make sure the developments are
going ok.
o The ducts are used to receive and transport gametes (there are male and female
specific version ones). Therefore, if something goes wrong in the development
here, you may have too many or too few/no ducts.
o Accessory glands secrete fluids into ducts and are also important for transport
of gametes.
o Perineal structures are collectively known as external genitalia, which is used to
determine sex.
Determination of sex:
Having all three of these as “female” confirms that the child is a female:
o Genetic sex = chromosomes
o Gonadal sex = gonads
o Genitals = internal (ducts) and external genitals
Male Reproductive System:
The primary spermatocyte after DNA replication undergoes 2 maturation divisions to
produce spermatids, which are a lot different morphologically than the primary
spermatocyte, so they have to undergo spermiogenesis (to shape them into normal
sperm cells).
,Sagittal picture
o The male gonad is the testis
o Epididymis is where sperm cells get collected when sperm cells are almost
matured. These can then travel to the Ductus deferens. Then they go through the
seminal vesicle, the prostate gland and the bulbourethral gland to finally be
ejected into the female vagina (upon the correct stimuli).
The brain is the key player in this scenario since the correct stimulus must be received
to get the sperm out, and also to get the whole process started. The Hypothalamus and
the Pituitary glands are necessary to get the testis kick started. The kick start occurs
during puberty so that testosterone gets made along with other hormones. Adrenal
glands and reproductive glands are also necessary. The sperm is created in
seminiferous tubules. They are then collected in the testis, then in the epididymis, then
into the ductus deferens to the ejaculatory duct and penile urethra. Fluids are secreted
from the seminal vesicles, the prostate gland, and the bulbourethal glands.
The generation of sperm cells is called spermatogenesis. The seminiferous tubules
contain spermatogonia, which are the first mitotic cell division before they go into
meisosis. These are stem cells, which can be used to create new sperm cells, but
always one sperm cell gets left behind, therefore, the male can stay fertile all his life.
Sustentacular cells sustain and promote the development of sperm cells by “feeding”
them hormones, hence they also produce hormones.
Details on spermatogenesis: gamete (haploid) production occurs starting from diploid
cells, hence Type A spermatogonia can sometimes duplicate themselves via mitosis,
while Type B spermatogonia are always going to become sperm via meiosis. These are
called primary spermatocytes. The products of meiosis however, are not identical to the
parent cells, or to each other. meiosis is used to increase genetic variation in the zygote.
Back to content:
The seminiferous tubules =>
, Spermatogenesis:
1. Spermatogonia: the stem cells in the seminiferous tubules undergo cell division
throughout adult life. Some of these differentiate into 2 primary spermatocytes
(still diploid), which prepare to being meiosis. One of these remain as
spermatogonium, while the second becomes a primary spermatocyte.
2. The one perforems meiosis I, therefore differentiates into secondary
spermatocytes (now haploid)
3. Secondary spermatocytes undergo meiosis II, producing spermatids
(undifferentiated male gametes), which are still immature.
4. Spermiogenesis occurs, where spermatids mature into spermatozoa. Here, the
acrosomal cap (made of fused saccules of the Gogli apparatus and filled with
perozisome, which disrupt the extracellular matrix) is formed.
5. Spermatozoa lose contact with the wall of the seminiferous tubule, and can now
enter the fluid of lumen.
Key cells:
o Sustentacular cells: these surround and enfold spermatids, phagocytocyze
cytoplasm shet by developing spermatids and provide nutrients and chemical
stimuli for development. They are also responsible for maintaining the blood-
testis barrier, and secreting inhibin (Inh), ABP and MIF
o Interstital/Leydig cells: make testostrone
o Spermatozoa: mature sperm cells
Mature spermatozoon lack the following, which
reduces sperm size and mass.
- ER
- Golgi
- Lysosmes
- Peroxisiomes
- Inclusions and other intercellular structures
Sperm anatomy:
Head: contains a acrosomal cap at the head
Neck: contains centrioles for continuous movement
of flagellum
Middle piece: contains mitochondria for energy for
the movement of the flagellum
The male and female reproductive organs are used for producing, storing, nourishing
and transporting gametes.
The process of fertilization is defined as the fusion of male and female gametes to form
a zygote
Definitions:
o The gonads produce gametes + hormones to make sure the developments are
going ok.
o The ducts are used to receive and transport gametes (there are male and female
specific version ones). Therefore, if something goes wrong in the development
here, you may have too many or too few/no ducts.
o Accessory glands secrete fluids into ducts and are also important for transport
of gametes.
o Perineal structures are collectively known as external genitalia, which is used to
determine sex.
Determination of sex:
Having all three of these as “female” confirms that the child is a female:
o Genetic sex = chromosomes
o Gonadal sex = gonads
o Genitals = internal (ducts) and external genitals
Male Reproductive System:
The primary spermatocyte after DNA replication undergoes 2 maturation divisions to
produce spermatids, which are a lot different morphologically than the primary
spermatocyte, so they have to undergo spermiogenesis (to shape them into normal
sperm cells).
,Sagittal picture
o The male gonad is the testis
o Epididymis is where sperm cells get collected when sperm cells are almost
matured. These can then travel to the Ductus deferens. Then they go through the
seminal vesicle, the prostate gland and the bulbourethral gland to finally be
ejected into the female vagina (upon the correct stimuli).
The brain is the key player in this scenario since the correct stimulus must be received
to get the sperm out, and also to get the whole process started. The Hypothalamus and
the Pituitary glands are necessary to get the testis kick started. The kick start occurs
during puberty so that testosterone gets made along with other hormones. Adrenal
glands and reproductive glands are also necessary. The sperm is created in
seminiferous tubules. They are then collected in the testis, then in the epididymis, then
into the ductus deferens to the ejaculatory duct and penile urethra. Fluids are secreted
from the seminal vesicles, the prostate gland, and the bulbourethal glands.
The generation of sperm cells is called spermatogenesis. The seminiferous tubules
contain spermatogonia, which are the first mitotic cell division before they go into
meisosis. These are stem cells, which can be used to create new sperm cells, but
always one sperm cell gets left behind, therefore, the male can stay fertile all his life.
Sustentacular cells sustain and promote the development of sperm cells by “feeding”
them hormones, hence they also produce hormones.
Details on spermatogenesis: gamete (haploid) production occurs starting from diploid
cells, hence Type A spermatogonia can sometimes duplicate themselves via mitosis,
while Type B spermatogonia are always going to become sperm via meiosis. These are
called primary spermatocytes. The products of meiosis however, are not identical to the
parent cells, or to each other. meiosis is used to increase genetic variation in the zygote.
Back to content:
The seminiferous tubules =>
, Spermatogenesis:
1. Spermatogonia: the stem cells in the seminiferous tubules undergo cell division
throughout adult life. Some of these differentiate into 2 primary spermatocytes
(still diploid), which prepare to being meiosis. One of these remain as
spermatogonium, while the second becomes a primary spermatocyte.
2. The one perforems meiosis I, therefore differentiates into secondary
spermatocytes (now haploid)
3. Secondary spermatocytes undergo meiosis II, producing spermatids
(undifferentiated male gametes), which are still immature.
4. Spermiogenesis occurs, where spermatids mature into spermatozoa. Here, the
acrosomal cap (made of fused saccules of the Gogli apparatus and filled with
perozisome, which disrupt the extracellular matrix) is formed.
5. Spermatozoa lose contact with the wall of the seminiferous tubule, and can now
enter the fluid of lumen.
Key cells:
o Sustentacular cells: these surround and enfold spermatids, phagocytocyze
cytoplasm shet by developing spermatids and provide nutrients and chemical
stimuli for development. They are also responsible for maintaining the blood-
testis barrier, and secreting inhibin (Inh), ABP and MIF
o Interstital/Leydig cells: make testostrone
o Spermatozoa: mature sperm cells
Mature spermatozoon lack the following, which
reduces sperm size and mass.
- ER
- Golgi
- Lysosmes
- Peroxisiomes
- Inclusions and other intercellular structures
Sperm anatomy:
Head: contains a acrosomal cap at the head
Neck: contains centrioles for continuous movement
of flagellum
Middle piece: contains mitochondria for energy for
the movement of the flagellum
