Blood vascular system of Balanoglossus.

Blood vascular system of Balanoglosis.

The blood vascular system of Balanoglossus consists of closed vessels, lacunar spaces, and a definite pulsating organ, generally known as the heart. The blood is colourless and has no or very few corpuscles; it may contain a few detached endothelial cells; it has no respiratory pigment. Most of the blood vascular system is located between the lamellae of the basement membrane and the leaves of the mesentery.There are two main longitudinal vessels, the dorsal, and the ventral vessels, running along the length of the body. The dorsal vessel is situated just below the alimentary canal and runs through the dorsal mesentery. The blood flows anteriorly through the dorsal vessel.

The ventral vessel is located in the ventral mesenteries and the blood flows posteriorly in it.These two vessels are highly contractile and they are all are composed of an inner endothelium surrounded by muscle layer.The dorsal vessel extends from the anus to the collar where it occupied a median position between two peri haemal cavities. The dorsal vessels are dilated at the front of the collar, forming a venous sinus which passes anteriorly into a central sinus or heart. The central sinus or heart is situated above the buccal diverticulum. Immediately above the central sinus, there is a triangular contractile epidermal sac called heart vesicle.

Blood from the central sinus enter the glomerular sinuses of the proboscis complex. In glomerulus, the blood is cleared of nitrogenous wastes. From the glomerulus, the blood is collected by four vessels. These vessels are regarded as the arteries because the blood leaving the glomerulus is considered to be purified.These arteries are.

1. A mid-dorsal proboscis artery,
2. A mid-ventral proboscis artery and two efferent glomerular arteries. The mid-dorsal and mid-ventral proboscis arteries supply blood to the proboscis.

The efferent glomerular arteries run backwards along the two sides of the buccal diverticulum. These vessels then run ventrally to encircle the buccal tube as the peri buccal arteries. The peri buccal arteries unite together ventrally to form a single longitudinal ventral vessel. The ventral vessel runs up to the posterior end of the body through the ventral mesentery.On its way, the ventral vessel gives out a ventral collar vessel to supply the collar.The collar tissue contains two distinct lacunar networks which communicate posteriorly with a ring vessel.The ring vessel is located in the collar-trunk septum. It arises from the ventral vessel and is connected with the dorsal vessel.A lateral pharyngeal vessel appears in the lacunar plexus at the junction of the two pharyngeal regions. The ventral vessel continued up to the anus and gives off lacunar networks all along the alimentary canal.The ventral vessel gives out an afferent artery to each gill-septum which bifurcates to supply the two adjacent tongue-bars.Thus, each tongue-bar receives two different branchial arteries which break up into a plexus. From this plexus, an efferent branchial vein is formed. It runs dorsally up to the middle of the tongue bar and joins with the efferent branchial vein of the adjacent tongue-bar. The common branchial vein opens into the dorsal vessel.The ventral vessel supplied blood through lacunar plexus to the body wall and alimentary canal.The blood from the intestine plexus in the trunk region is collected mostly by the dorsal vessel.

Coelom in Balanoglossus.

Coelom in Balanoglossus.

The coelom is enterocoeles having been formed as our growths of the enteron and is lined with coelomic epithelium or peritoneum.It is divided into three portions, corresponding to the three body regions. They are proboscis coelom, a pair of collar coelom, and a pair of trunk coelom.

1. Proboscis coelom.
2. Collar coelom.
3. Trunk coelom.

1. Proboscis coelom.

It is also known as protocoel. It is a single space in the proboscis which is largely occupied by muscles and the connective tissue and a few structures like buccal diverticulum, glomerulus, and central sinus or heart. Dorsally, towards the posterior side, the proboscis coelom is divided by a dorsal mesentery into right and left dorsolateral compartments; the left compartment is larger than the right.Ventrally it is divided by a ventral mesentery into right and left ventrolateral compartments.

2. Collar coelom.

It is also known as mesocoel. It has two cavities lying side by side in the collar , one on each side of the collar wall and the buccal cavity.It doesn't communicate with the proboscis coelom, but posteriorly, its each cavity opens into the final gill sac of its side by a canal called collar canal. They open to the exterior by a collar pore.

3. Trunk collar.

It is also known as metacoel. It has closed cavities lying between the wall and alimentary canal. The two cavities are separated by an incomplete dorsal and a complete ventral mesentery. In the branches-genital region, each cavity is further divided by a lateral septum into a dorsal-latera and ventral-lateral compartments. They are obliterated by the coeloms musculature.

Coelomic fluid.

Both two types of the coelom I,e proboscis and collar coeloms communicates with the exterior and get filled with sea water through their pores, which keeps them the target. They are filled with the watery coelomic fluid heaving amoeboid coelomocytes and are originates from the coelomic epithelium.According to the Spengel, the coelomic fluid behaves like leucocytes by secreting a membrane around any foreign body that may invade the animal.

Reference.

Aggarwal Sarita. A Text Book of Biology, New Delhi.: Madhuban Educational Books, 2011.

Bhamrah, H.S., and Kavita, Juneja. A Text Book of Invertebrates, New Delhi: Anmol Publications Pvt Ltd, 2011.

Jordan E.L. and P. S., Verma. Invertebrate Zoology, New Delhi,: S. Chand and Company Pvt. Ltd., 2011.

Kotpal, R. L., Modern Text Book of Zoology: Invertebrates, New Delhi, India: Rastogi Publications,2011.

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