Late anaphase
6.3 HUMAN REPRODUCTION
Thus far we've looked at the structure of male and female reproductive systems and gametogenesis.
A quick review of the various parts: the male system is made up of a pair of testes, the male gonads, located in the scrotum - the testes containing seminiferous tubules lined by germinal epithelium that produce sperm/spermatozoa by spermatogenesis; the various tubes responsible for carrying the sperm and related fluids and nutrients to the outside of the body viz. the epididymis, the vas
deferens, the ejaculatory duct and the urethra; the secretory glands which produce the fluids and nutrients viz. the seminal vesicles, the prostate gland and the pair of Cowper's glands; and the external reproductive organ - the penis through which the urethra runs opening at its tip. HR!
A noisy class this. Some are sharing in the review by providing the information and following through with the diagrams in the text; some are engaged in their own discussions not in the least related to the review; and some though silent and looking at me are a million miles away - their glazed expressions tell a story of its own. HR2
The female reproductive system made up of a pair of ovaries in the lower abdomen, the female gonads, lined by germinal epithelium which produces the follicles within which oogenesis takes place to produce the ova or eggs; a fallopian duct or oviduct which carries the egg or ovum from the ovary to the uterus; the pear-shaped, hollow organ with muscular walls - the uterus or womb - which becomes lined with a highly vascular, that is: rich with blood vessels, endometrium on a regular basis; the neck of this pear-shaped uterus being the cervix which leads to the vagina or birth canal; and then to the outside by the vulva. Remember that when fertilization occurs the foetus is attached to and develops within the uterus. HR3
For those sharing in the review it's a case oflearning the language - what the new words are, how to pronounce them and the fear of forgetting this additional language that must be learnt! HR4
With gametogenesis the germinal epithelium divides by mitosis to produce a diploid/2n
spermatogonium in the testis - in the sexually adult male; and a diploid/2n oogonium in the ovary - of the developing female embryo. Each of these then grows to form a primary diploid spermatocyte in the testis and a primary diploid oocyte in the ovary. Each of these then goes through meiotic divisions. The primary diploid spermatocyte after the first meiotic division forms two secondary
spermatocytes and after the second meiotic division forms four haploid spermatids which will grow and form the haploid sperm cells. HR5
Inthe sexually adult female a single diploid oogonium grows and becomes a primary diploid oocyte that then divides by meiosis. The first meiotic division produces a small first polar body and a much larger secondary oocyte. The secondary oocyte goes through the second meiotic division to produce a small second polar body and a much larger haploid ovum. HR6
Why the need for the meiotic divisions? Meiosis allows for a reduction in the number of
chromosomes in the sex cells - to half that or the haploid number as compared to an ordinary cell with the complete or diploid number of chromosomes. This is what allows for the new individual that is formed to then have exactly the same number of chromosomes as each of the organisms within the species. For human beings a diploid cell has 46 chromosomes and a haploid sex cell viz.
an egg/ovum or a sperm has only 23 chromosomes each. This means when a sperm fuses with an egg the new individual or zygote will have in it 46 chromosomes - the same number as in each and every human being. HR7
Now let us look at ovulation and menstruation. What does the term ovulate mean. Does that mean just before a girl gets her periods? Does that mean the period itself? It's obvious that those
participating in the lesson do not know. My voice expresses my frustration as I try to lead towards the meaning - something to do with the egg ... I finally give up and share the meaning: it refers to the release of the egg! HR8
When a female reaches puberty two things happen: she begins to develop secondary sexual
characteristics and she begins to ovulate and menstruate. She now releases an egg and also has her periods if the egg is not fertilized. The very first egg that the female releases could be fertilised by a sperm - so this means the female can become pregnant. The body's message from the very first period is: I am now capable of reproducing; I am sexually mature! HR9
I am going to try and explain what happens using a twenty eight-calendar day cycle. This is the average for females that are ovulating and menstruating. Remember that average means there are females who fall outside the twenty eight day range. Also, when a female first begins to menstruate her cycle could be irregular - she may menstruate every several months. So there is no way of
Let's start with Day 0 of the twenty-eight day cycle being the onset of the period. The female begins to menstruate. What causes this? If an egg has been released and has not been fertilised there is no need for the endometrium lining the wall of the uterus. This endometrium now begins to break away and this breaking away is aided by contractions of the muscular walls of the uterus. And that's when I hear some of you sharing that you are having such terrible period pains! On average it takes approximately seven days for the lining to be removed from the uterus. Immediately after that a new one begins to be laid down - in preparation for the next possible fertilized egg. HR11
I notice that the class is silent. I have everybody's attention! Even the glazed looks from those that were miles away have gone. They are all paying attention to what I am sharing with them. Does this mean that they did not know of the mechanics of ovulation and menstruation? HR12
± 14 days after the onset of the period another egg is released and enters the Fallopian tube. If there are sperms in the vicinity the first to reach the egg will fertilize it. If the egg is not fertilized it will degenerate after a few days. Depending on when the egg is released it would be safe to say that fertilisation could occur in any time between day 10 and day 18 after the onset of the period. Where does the egg come from? Itcomes from the follicle in which it was formed. A large follicle with a mature ovum is called a Graafian Follicle.Itis the follicle that releases the hormone oestrogen that will prepare the endometrium lining for the implantation of a fertilised egg or zygote. So the unsafe period for unprotected sex is on average between days 10 and days 18 - it is during this time that there is a great likelihood that a female could fall pregnant. I wonder is it this that learners do not know and why we have a high rate of teenage pregnancies? Is this also why the male often claims that he cannot be the father of the child? HR13
This galvanises the class. I am told that there are learners in Grade 11 about to become parents- something that teachers and management do not know of as yet. The female learner has not been to school for some time while the male is at school every day. An uproar ensues. Why is it that males get away with this and it is the female who is left to suffer the consequences? Ittakes two to tango and both should be responsible. But not all teenage boys think this way. Well, if a teenage boy is that immature then he should not partake in sex. The debate rages on. HR14
Waseela now shares her thoughts. (Gone is the Waseela who wanted only biology). Itis always the girl who is undermined; the one who is seen as doing all that is wrong in society; and who is always
called bad names. Noelene enters the fray - just because she's walking around with a big stomach.
Waseela continues: the girl cannot come back to school while the boy carries on as normal. If the girl has to come to school she will be picked on. HR15
I then ask if it is possible that only the female is responsible for a pregnancy given what I had just shared with the class from a biological position. The class in unison chorused ever so loudly:No ways! HR16
Nolwande then shared her experience. Her teenage sister fell pregnant. The pregnancy and the child were both accepted. The child was born and the father comes to her home and assists in raising the child. His family also provides financial support for the child. This is how it is done in her culture in the township. She also shares that her father has warned of dire consequences if she had to fall pregnant. Tivashni expressed that if she fell pregnant she would have to get married and have the child together with being disgraced in her community. For Tivashni her community is not accepting like Nolwande's. HR17
Trust Kaiser to add to the debate! His neighbour fell pregnant. She herself was uncertain as to who the father was - she had shared this with Kaiser. To make sure the baby was supported financially she identified one person as the father. This male, also a friend of Kaiser, accepted the baby as his responsibility. Kaiser was in a dilemma - did he tell his friend the truth or not. This added to the burning issues in the class and two-timing girls were now part of the discussion. Nolwande confirmed that this was part of her experience as well and that witchdoctors were often asked to confirm the paternity of the child. I noticed that nobody spoke of two-timing males! HR18
And suddenly there was Naseema's booming voice. In no uncertain terms she stated that an unmarried pregnant female was a disgrace to both her family and community. There was no place for this in Naseema's world. For Naseema, in a pious Muslim family where the male head of the household was also a community leader this was totally unacceptable. This would also be true if the female had been raped. Under those circumstances Naseema, who stated clearly her abhorrence to abortion, suggested that perhaps abortion would be an answer to take away from the disgrace to the family and any other unmarried female daughters in the house. This would also prevent the
community from being disgraced. HR19
The class shouted her down. For the first time Wonderboy spoke in my class. He had never ever spoken previously. Even if! asked him a question he was never prepared to speak. The Black learners laughed on hearing Wonderboy's voice - in a way that seemed strangely, to me, encouraging. The class became quiet - it was as ifnew ground was being broken. Wonderboy shared with us a saying in Zulu that he then translated for our benefit: A child is a gift from God.
He went on to share that since this was the case humans have no right to destroy that which is a gift from God. HR20
I looked at my watch. Ten minutes to go before the hour's lesson ended. I took over again. I shared that learners needed to think through issues raised by themselves during the lesson. I stated: let's go back to the Graafian Follicle. At intervals of approximately every four weeks a follicle ruptures to release a mature ovum or egg. This is called ovulation. The ovum enters the Fallopian tube and moves through to the uterus. The ruptured follicle is now called a corpus luteum which, if a pregnancy occurs, will secrete the hormone progesterone to maintain the pregnancy. If fertilisation has not taken place then the corpus luteum degenerates and no progesterone is produced. This results in the endometrium lining breaking away from the uterine wall once again and being sloughed off. A period has started again and with it a new twenty-eight day cycle. HR21
The buzzer sounds. The class gathers their things together and leave. They're arguing with each other again. The lesson has disturbed them and their sense of disquiet reaches out to me. HR22