Reproduction In Organisms

Meiosis is the process that reduces the number of chromosomes from diploid to haploid in cell division in sexually reproducing species. The process requires two consecutive nucleus divisions and helps in the development of animal reproductive cells (gametes). It also leads to the development of spores in fungi, plants, and most algae. 

The process of Meiosis begins when the duplicated chromosomes condense in the middle of the nucleus and sets of homologous chromosomes cross over, sharing some of their genetic material.

To determine which statements regarding the female reproductive cycle are correct, we need to evaluate each statement:

1. In non-primate mammals, cyclical changes during reproduction are called oestrus cycle. This statement is correct. In non-primate mammals, the reproductive cycle is termed the oestrus cycle, which differs from human menstrual cycles.
2. First menstrual cycle begins at puberty and is called menopause. This statement is incorrect. The first menstrual cycle at puberty is called menarche, whereas menopause refers to the cessation of menstrual cycles later in life.
3. Lack of menstruation may be indicative of pregnancy. This statement is correct. One of the common signs of pregnancy is the absence of menstruation, although there can be other causes for missed periods.
4. Cyclic menstruation extends between menarche and menopause. This statement is correct. Cyclic menstruation occurs regularly from menarche (the onset of menstruation) until menopause (the end of menstrual activity).

Based on the evaluation, the correct answer is: A, C and D only.