Reproduction

1. Pila reproductive system

2. Pila is dioecious and shows sexual dimorphism. Male has a
smaller shell, a less swollen body whorl and a more
developed penis than the female.
Male reproductive system
1. Testies:
It is single and lies close to digestive gland, appears quite
distinct on account of its creamy colour.
It is separated from the shell by a thin cutaneous
membrane. Two types of sperms are produced in the testis
eupyrene, and oligopyrene.
Eupyrene sperms are small, thread-like, about 25.0 µ long
and 1.2 µ broad, and with distinct head, middle piece and
tail with a cilium. They are motile and can fertilize ova.
Oligopyrene sperms are large, spindle shaped, about 32.5
µ long 3 µ broad with distinct head, middle piece and tail
of 4 or 5 cilia. They are non-motile, incapable of
fertilization and probably have some other function.

3. • 2. Vasa efferentia:
• Several fine ducts, the vasa efferentia, arise from the different regions
of the testis and unite to form large common ducts the vas
deferentia.
• 3. Vas deferens:
• It is differentiated into three distinct regions
• (i) one proximal tubular part
• (ii) vesicula seminalis and
• (iii) Terminal glandular part.
• Proximal parts of vas deferens are narrow and thin walled. It runs
along the inner border of digestive gland upto the posterior renal
chamber and then it runs to the left.
• After reaching the pericardium it opens into the ventral side of
vesicula seminalis. Vesicula seminalis is a somewhat curved, swollen
and flask shaped structure with a blind rounded posterior
prolongation.
• It serves as a storehouse for the sperms. Its narrow tubular end leads
into the glandular part. This part runs forward into the left side of the
rectum.
• It finally opens outside by the male genital aperture, at the tip of
which genital papilla, which is a miniature second penis is situated.

4. • 4. Penis:
• It is a copulatory organ situated in front of the
anus and remains enclosed in a thick glandualr
flap, the penis sheath when not in use is a long
stout and slightly curved flagellated structure with
a swollen base and a tapering free end. It is highly
extensile; being about 1.5 cm long but can attains
a length of 4 cm during copulation.
• 5. Hypobranchial gland:
• At the base of the penis sheath is an oval,
glandular thickening with pleated surface, the
hypobranchial gland.
• It consists of tall cells containing small basal
nuclei. Due to absence of duct its secretions are
released directly upon its surface

5. • Female reproductive system
• Ovary:
• It occupies the same position as the testis in male but
is less extensive. In mature females it is branched and
dark coloured.
• Branches of the ovary or acini are single layered and
flask shaped structure. Their outer rounded end is
closed and the inner slender tubular end unites to form
a single oviduct.
• Oviduct:
• It is narrow and transparent tube like structure. It
arises from the middle of the ovary and runs along the
inner margin of the digestive gland. Near the renal
organ it turns downwards and then upwards to open
into the receptaculum seminis.

6. • Receptaculum seminis:
• It is small bean shaped and lies enclosed within the cavity
of posterior renal chamber. It is attached closely to thin
walled pouch, arises from the wall of uterus and is called
pouch of receptaculum. It is meant for storing the sperms
received from the male Pila during copulation.
• Uterus:
• Large yellow and pear shaped uterus lies below the
intestine and to the right of the renal chamber. It
communicates receptaculum seminis to the vagina.
• Vagina:
• A white cream –coloured tubular vagina runs along the
left side of the rectum in the branchial chamber.
• It opens outside a little behind the anus through female
genital aperture situated on a small papilla.

7. • Copulatory apparatus:
• A rudimentary penis lies beneath a
glandular fold of the mantle. It is a thin
flagellar structure nearly 6.0mm long
and pointed at the tip.
• Hypobranchial gland:
• In female it is poorly developed with a
rudimentary glandular thickening.

8. • Breeding and development
• Breeding in Pila takes place in the rainy season. It involves three processes: copulation,
fertilization and laying.
• Copulation:
• Copulation may occur in water on moist land. It takes about 3-4 hrs. The male and female snails
come together facing one another with their right nuchal lobes lie opposite to one another.
• The penis of the male elongates along with its sheath and its proximal end comes in contact with
the male genital aperture and the distal end passes into the mantle cavity of the female and finally
to its genital aperture.
• Now the seminal fluid is shed into the vagina of the female where it migrates to be stored into the
receptaculum seminis. After that, both separates
• Fertilization:
• Fertilization is internal in Pila. It takes place in the uterus, where both ova and spermatozoa pass,
the former from the ovary and the latter from the receptaculum seminis.
• Laying:
• Egg laying starts 2 or 3 days after copulation. The eggs are laid in sheltered places (holes and
crevices) or moist land near water.
• A single female lays 200-800 eggs at a time. The eggs are rounded, about the size of the pea seeds
and covered by whitish shell. They contain a good deal of food.

9. • development
• Development occurs outside the body of the female. The parents do not
incubate or look after the eggs. Development of Pila is direct. The embryo
floats in a central core of liquid albumen which is surrounded by a thick
layer of whitish solid albumen.
•
• During development the visceral mass and the shell of the embryo
becomes spirally coiled and the characteristic phenomena of torsion takes
place. This results in the asymmetry of the body. The young snails
hatching from the eggs are similar in form to the adult.