Page 144 - EFI-RAV ZILBERSTIN_VOL 8.EFI-RAV ZILBERSTIN_VOL 8.1A

Pg: 144 - 5-Front 21-10-31

three [single] chromosomes is from the husband’s sperm
cell and the other set is in the wife’s ovum that awaits fertil-
ization. One of the explanations advanced for this doubling
of the chromosomes is to cover up genetic defects. For ex-
ample, if there is a defect in chromosome number 12, the
corresponding chromosome [of the matching set] can com-
pensate for the defect. Another example is when a chromo-
some lacks the instruction for the manufacture of a certain
protein – the missing instruction will then be supplied by
the corresponding, normal chromosome2.

At fertilization, the twenty three chromosomes of the
sperm unite with the twenty three chromosomes of the
ovum thereby fertilizing it, so that it actually becomes the
first [complete] fetal cell. From this moment on, the fetus
develops. This single cell divides into 2, 4, 8 and then 16 cells,
and when there are 256 cells. An order is conveyed that each
group of cells should fulfill a specific function: this group of
cells develops into the head, these into legs, those into hands
etc. In order for all these orders to be carried out precisely,
as far as the medical and scientific worlds understand, the
genes in the developing cell must be aligned with utter pre-
cision, without the slightest deviation. It is well known that
the extra doubling of one section of a chromosome results in
the birth of a child with Down syndrome and if part of one
of the chromosome bundles is missing the fetus will suffer
from some other defect. [Some defects are incompatible
with life while others are not.]

It therefore appears that there can be nothing more ru-
inous than two sperm cells entering an ovum at exactly the
same time because each chromosome will be a triple rather
than a double chromosome and as we have seen, even a sin-

2. At this point Dr. Gat describes further wonders with which the Creator has
invested this process, though here we only quote what is relevant to the topic
under discussion.

128 1 Medical-Halachic Responsa of Rav Zilberstein